do you proptect cast iron boiler from below 140 when running an

shy_2

are you concerned about below 140 temp when running the indirect hot water htr loop(older peereless partner inst say
with 119,80and 60 with reduced input condensation could occur)

they now recomend conden boiler

this job is casat iron

if concern how would you protect

hr

Generally

the boiler would not run extended periods below condensing temperatures for DHW production. Normally an indirect is not sized, or pumped, in such a way to outstrip the boilers output rate. So I would say within 10 minutes or so the boiler should be warmed up above condensing range. This is another reason to use priority controls for DHW. Allowing the boiler to push all the output into the indirect while the heating zones are shut down for a short period.

There are a number of ways to pipe, and control a boiler to protect against cold return temperatures for extended periods. Most all tekmar controls offer return protection. Merely use PS piping and mount the sensor to watch the temperature at the return connection to the boiler. The control would shut down the boiler pump until the boiler temperature comes above condensing point.

This can also be done with a "Thermal Clutch" using a variable speed circ on the boiler loop to vary as the temperature changes instead of a bang bang control to stop flow completely. I have used this method on wood fired boilers to keep them in a hot, gasification range.

Should be some more delta T pumps on the shelves soon to aid in this installation

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,128051,00.html

hot rod



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